Capability of Cartilage Extract to In Vitro Differentiation of Rat Mesenchymal Stem Cells (MSCs) to Chondrocyte Lineage

The importance of mesenchymal stem cells (MSCs), as adult stem cells (ASCs) able to divide into a variety of
different cells is of utmost importance for stem cell researches. In this study, the ability of cartilage extract to
induce differentiation of rat derived omentum tissue MSCs (rOT-MSCs) into chondrocyte cells (CCs) was
investigated. After isolation of rOT-MSCs, they were co-cultured with different concentrations of hyaline
cartilage extract and chondrocyte differentiation was monitored. Expression of MSCs markers was analyzed via
flow cytometry. Moreover, expression of octamer- binding transcription factor-4 (Oct-4), Wilm's tumor
suppressor gene-1 (WT-1), aggrecan (AG), collagen type-II (CT-II) and collagen type-X (CT-X) was analyzed
using RT-PCR on 16, 18 and 21 days. Furthermore, immunocytochemistry and western blot were performed for
CT-II production. Finally, proteoglycans (PGs) were examined using toluidine blue and alcian blue staining. The
phenotypic characterization revealed the positive expression of CD90, CD44 and negative expression of CD45 in
rOT-MSCs. These cells also expressed mRNA of Oct-4 and WT-1 as markers of omentum tissue. Differentiated
rOT-MSCs in the presence of 20 µg/ ml cartilage extract expressed AG, CT-II, CT-X, and PGs as specific
markers of CCs. These observations suggest that cartilage extract is potentially able to induce differentiation of
MSCs into chondrocyte lineage and may be considered as an available source for imposing tissue healing on the
damaged cartilage. More investigations are needed to prove in vivo cartilage repair via cartilage extract or its
effective factors.